Co-Authored with Karli Barton, Field Research Technician, OMAFRA-Ridgetown

As colder weather approaches, we have the opportunity to identify overwintering locations for the invasive brown marmorated stink bug (BMSB). BMSB and a few other stink bugs like to move into homes and other sheltered areas for the winter. This is a great time for homeowners dealing with this nuisance to help with citizen science and alert us to new locations. The brown marmorated stink bug is an invasive species from Asia that was first introduced to Pennsylvania in the late 1990s, causing major economic losses in agricultural production. It has since moved into a number of states and provinces, including Ontario. This invasive species has over 300 known hosts including a variety of fruit trees, berries, grapes, vegetables, field crops including corn, soybeans and edible beans, ornamental trees, and ornamental shrubs.

BMSB spend the winter months in houses and move onto their host plants during the warmer months. Although the insect has not yet been observed in field crops in Ontario, established breeding populations have been confirmed in a few urban locations. The extremely mobile nature of this insect during the growing season means that it is difficult to scout and monitor. Alternatively, overwintering locations can serve as a fixed location for monitoring and can provide reliable information about the risk level of BMSB. We often establish field survey locations near these hihg risk locations where they have been observed by homeowners. With colder weather coming, it is likely that homeowners may begin to encounter these in their homes.

Figure 1. Confirmed homeowner finds and established breeding locations of BMSB in Ontario.

If you think you have found BMSB in homes in locations not represented on the map, please contact the OMAFRA Agriculture Information Contact Centre at 1-877-424-1300 or send an email with good quality photos to ag.info.omafra@ontario.ca.

Figure 2. Distinguishing Characteristics of BMSB.

There are a couple identifiable characteristics that can be used in distinguishing BMSB from look-alikes:

White bands on its antennae

Distinct white triangles in a pattern along its abdomen

The edge of its pronotum or “shoulders” is smooth

You can also visit our website for additional photos, infosheets, ID postcards, and potential management options at ontario.ca\stinkbug.

The Trochanter mealybugs Pseudococcussorghiellus (Forbes) are small (at most 2mm), whitish, wax-covered insects that feed on plant roots (Fig. 1). Because of their size and life history, they are often overlooked but have been found in Southwestern Ontario. Trochanter mealybugs are part of a family of unarmored, scale insects that enjoy moist climates (Mani and Shivaraju 2016).

Figure 1. Close up picture of a Trochanter mealybug feeding on Soybean roots. (credit: K. Sim)

More specifically, Trochanter mealybugs are root mealybugs and usually go unnoticed because they live and feed on the roots of soybeans (Fig. 2) and many other plants such as alfalfa, red and white clover, and corn. The affected soybeans may look like they have a potassium deficiency with yellowed leaf margins and/or stunted growth (Mani and Shivaraju 2016). It is native to the United States where it is considered a pest. There have been sightings of this species in Southwestern Ontario for a few years but have only been found in small patches and thus do not seem to cause much harm.

Figure 2: Trochanter mealybugs on a soybean root. (credit: K. Sim)

When mealybugs are young, they can move short distances from one plant to the next quite easily. They can also move with irrigation water; the waxy covering on their bodies helps them survive in water but their dispersal ability is quite limited (Mani and Shivaraju 2016).

This summer, probably because of the wet spring, the Trochanter mealybug has been sighted in a soybean field in Harrow as well as a field near Chatham (O. Wally Pers. Comm.). Because of its patchy distribution and the fact that it does not seem to be doing much damage there is no need to panic but keeping an eye out for them is a good idea so that the distribution of this species can be monitored in the region. If, in your field, you see a patch of stunted soybean plants or think they may have potassium deficiency, pull out one of those plants and check the roots (Fig. 2). If there are oval waxy insects crawling around on the roots or in the soil surrounding it, you will know that there are trochanter mealybugs in that patch and your plants do not have a potassium deficiency.

If you do find the Trochanter mealybug in your fields, please do not hesitate to contact me (julia.mlynarek@canada.ca or 519-738-1227).

]]>http://fieldcropnews.com/2017/08/keeping-an-eye-out-for-trochanter-mealybugs-in-soybean/feed/0The Season is Not Over Yet for Late Season Pests Like Bean Leaf Beetle, Soybean Aphids and Othershttp://fieldcropnews.com/2017/08/the-season-is-not-over-yet-for-late-season-pests-like-bean-leaf-beetle/
http://fieldcropnews.com/2017/08/the-season-is-not-over-yet-for-late-season-pests-like-bean-leaf-beetle/#respondFri, 18 Aug 2017 15:48:20 +0000http://fieldcropnews.com/?p=14114

Despite it being the middle of August, some pests are not showing signs of wrapping this season up. Bean leaf beetle are a particular concern in food grade IP and seed soybeans and edible beans across Ontario. As are pod piercing pests like stink bugs and tarnished plant bugs. Soybean aphids are also increasing in numbers, particularly in fields in Eastern Ontario. So scouting is not over yet , I am afraid.

Bean leaf beetle pod damage. H Bohner, OMAFRA

Bean leaf beetlecan feed on the leaves, although the defoliation they do rarely reach threshold levels to impact yield this time of year. It is their pod feeding that can be a concern, especially in the later R stages of pods. Pod feeding can open the pods up to the development of pod diseases, impacting quality. Bean leaf beetle can also clip pods off of the plants which can have a direct impact to yield.

Scouting and Thresholds:

For R4–R6 Stage of IP, Food Grade and Seed Soybean and Dry Bean Fields – Assess 20 plants in five areas of the field. Avoid the field edge. Determine the percent defoliation and the number of pods damaged or clipped off and make note of the presence of adults.

For Soybeans: If 10% of the pods on the plants have feeding injury AND the beetles are still active in the field, a spray is warranted. If pods are being clipped and found on the ground, an application is warranted if beetles are still active in the field. Consider days to harvest intervals before making a spray decision.

For Dry Beans: With higher value and stringent quality standards in dry edible beans, if 5%–8% of the pods inspected have feeding scars, control may be necessary. If pods are being clipped and found on the ground, an application is also warranted. Ensure that adults are still presently active in the field before a spray is applied. Consider days to harvest intervals before making a spray decision.

Brown stink bug on soybeans. T. Baute, OMAFRA

Stink bugs and tarnished plant bugs feed directly on pods and seeds. Both the adults and nymphs have piercing and sucking mouthparts for removing plant fluids. They inject digestive enzymes into the seeds, causing the seed to dimple or shrivel, resulting in picks. The feeding wound provides an avenue for diseases to gain entry into the pod. Seed quality is reduced. Indirect effects can include delayed maturity — green bean syndrome —of injured plants, though stink bugs are not the only cause for green bean syndrome.

Scouting and Thresholds:

Take 20 sweep samples (in a 180° arc sweep) in five areas of the field. Determine the average number of adults and nymphs
per sweep by dividing the total count by 100.

Stink bugs in Soybeans – Control may also be necessary in identity preserved (IP) food-grade and seed soybeans in R4 to early R6 stage,
if an average of or 0.2 bugs per sweep is found (or 20 bugs in 100 sweeps). Even in crush beans, control may be warranted if an average of
0.4 adults or nymphs per sweep is found during the R4 to early R6 stages of soybeans.

Tarnished plant bug (TPB) in Dry Beans – Treatment may be required when an average of one to two tarnished plant bugs (nymphs
or adults) per sweep is found during the pod stages.

Seven spotted lady beetle feeding on soybean aphids. T. Baute, OMAFRA

Soybean aphids are increasing in numbers per plant, particularly in Eastern Ontario. Some fields in southern Ontario have experienced a significant drop in aphid numbers, likely in part due to natural enemies.

Scouting and Thresholds:

Fields that have aphids present should be scouted every 7–10 days until the crop is well into the R6 stage of soybeans. Scout fields more frequently (every 3–4 days) as aphid populations approach the threshold. Look at 20–30 random plants across the field. Avoid field edges. Estimate the number of aphids per plant in that field and the abundance of natural enemies present. A minimum of two field visits is required to confirm that aphid populations are increasing. The threshold for soybean aphids is 250 aphids per plant and actively increasing on 80% of the plants from the R1 up to and including the R5 stage of soybeans. More aphids per plant are needed once soybeans are in the R6 stage. Beyond the early R6 stage, economic return from any insecticide application is not likely and pre-harvest intervals have been reached.

Natural enemies play a big role in taking soybean aphids down below threshold, especially when aphid pops are just hovering below or above the threshold. Making observations of natural enemy presence can help you determine if a spray will be necessary. Use the free Aphid Advisor app, plugging in the number of aphids you see, as well as natural enemies. The app will calculate the number of aphids that will be fed on based on the natural enemy and aphid population and determine if a spray is necessary.

We are still seeing WBC trap counts going up in most counties north and east of Perth. That means that WBC moth flight has not yet peaked in those counties. This is important because this also means that we haven’t reached peak egg laying in those counties and that there are a wack of moths flying around looking for somewhere to lay their eggs. Where do they go this time of the season? Late planted corn fields that are still in the early pollination stages (i.e. silks have not dried down yet) and edible beans.

For edible beans, it is not as straight forward. Unlike in corn, WBC are nearly impossible to find in dry bean fields until pod feeding begins. Trap thresholds used in Nebraska have been found to be too high for the Great Lakes Region. So we rely on research and experience from Michigan State University. Pheromone traps can still help indicate which fields are at greater risk though. Traps at dry bean fields that capture an accumulation of 50 or more moths per trap are likely at greater risk and require scouting for pod feeding.

Pod feeding is expected to begin 10 to 20 days after peak moth flight has occurred, as indicated when trap counts begin to decline after weeks of steady increase. Prior to pods being present on the plants, scouting for egg masses in adjacent cornfields can also help determine what the local WBC populations are like. If any of the corn fields in the immediate area are past early tasseling, the dry bean fields will be more attractive for the moths. If an adjacent corn field reached the corn egg mass threshold and required spraying, the dry bean field is also likely at risk.

Once pods are present, scout 100 plants (10 plants in 10 areas of the field). Look for signs of early surface feeding or holes going directly into the pod. If pod feeding is easily found, a spray application is necessary. Control is still very effective when done as soon as pod feeding is found. WBC exit and enter new pods each night, so insecticides still work at controlling the larvae, as long as the pods are present during the application so that there is residue left on the pod surface.

Spraying too early when pods are not present on the plants will not protect the crop from damage. Spraying too late, when pod feeding has been taking place for some time will not reduce the risk of seed damage and pod disease incidence. The key is to protect the plants when the larvae are feeding on the pods.

We are continuing efforts in researching WBC in dry beans. A collaborative effort is underway this summer with OMAFRA (Meghan Moran and myself), UGRC (Chris Gillard) and Hensall District Co-op (Jim Barclay), collecting data from a number of side by side corn and dry bean fields, in hopes of increasing our understanding of this pest and dry bean risk factors.

I’m seeing a lot of pics on Twitter of recent WBC moth catches in traps, which I think is great. The more people that are trapping, the more data we have to work with to determine when peak flight takes place and when scouting is required. But trap counts do not indicate if a spray is required in corn. There is no relationship between trap counts and WBC infestation levels in the corn field that the trap is positioned at. Traps are used for only two purposes. 1) to indicate whether or not moths are flying in your area (especially for those locations other than the normal hotspot regions of Bothwell and Tilsonburg since sadly, these areas always have them) and 2) to indicate when peak moth flight occurs since this is followed shortly thereafter by peak mating and egg laying. Peak flight means scouting time!

We see moths flying around as early as mid June and it is normal to see catches increase over time. Peak flight varies each year and for each county or region but typically occurs sometime during the third week of July, forth week of July and first week of August. So having a number of traps set up in each region and county helps us to determine which week peak flight takes place for any given location. Even if you don’t have a trap, you can still see the interactive trap maps for this year and see what is going on in your county here via OMAFRA AgMaps.

Where a relationship does exist is between the crop stage and egg laying. Female moths try their best to lay their eggs on plants that have a tassel developing in them. WBC larvae do not feed on the corn leaves so if there is no tassel tissue, the larvae starve. Spraying eggs or larvae prior to any tassel being available on the plant is of no value at all, since the larvae are going to die anyway. You are best to target both scouting and spraying during the ideal egg laying period which follows shortly after peak moth flight. Pre-tassel to full tassel stage is the most attractive stage for the moth to lay her eggs. Fields in the pre-tassel to full tassel stage during and shortly after peak flight are most at risk. Once the corn field is beyond full tassel stage and the tassel is spent, moths prefer to go to dry beans or later planted corn fields nearby.

Scout fields or areas of field according to their growth stage. Knowing that peak flight occurs within in a three week window from the third week of July to 1st week of August, scout fields according to their growth stage during that period. Each week the stage will change so focus each week on those in pre-tassel to full tassel stage. Scout all corn fields, regardless of their Bt trait with the exception of those with the Vip3A trait. Only Agrisure Viptera hybrids provide effective control against WBC. All other Bt traits no longer provide protection against this pest and should be scouted.

Scout 10 plants in 10 areas of the field looking for egg masses on the top two to four leaves of the plant. If a field is quite variable, with different areas in different stages at one time, go to the area(s) in the ideal crop stage that week and scout those plants. The next week, a different area of the field may be at risk. Moths are more likely to stick around in the same field for a few weeks, instead of leaving to go to other fields, if she can find an areas that has plants in the ideal crop stage.

Use cumulative counts to determine if threshold has been reached. A spray is required if you find an accumulation of 5% of the plants with egg masses or small larvae over a two to three week period during pre-tassel to late tassel stages.

Time the spray application close to when fresh silks are present. This is when the majority of the larvae will have made their way to the silks to feed on before entering the ear. Tankmixing with fungicides for ear mold protection during this time will help provide protection from both WBC and ear rots.

To reduce the risk of resistance to an insecticide, rotate between chemical families each year or use an insecticide that contains two modes of action. Follow buffer zones on product labels to reduce the risk of non-target exposure of pollinators and aquatic invertebrates.

More insecticide information, life cycle, images and guidelines can be found at:

Despite the wet weather, potato leafhoppers (PLH) are thriving in many areas of the province. Hopperburn is evident in the second crop of alfalfa, though dry bean fields are also at risk, especially once insecticide seed treatments are no longer present in the plants. Unfortunately, once hopperburn is noticed, yield and quality has already been compromised. Though PLH-resistant varieties of alfalfa are available, new seedings are still vulnerable, as the glandular hairs are not fully expressed the first year. Use the conventional thresholds below for first year seedings of these resistant varieties.

Hopperburn from potato leafhopper. Photo: G. Quesnel

Scouting in alfalfa: Scout every 5–7 days. Take 20 sweeps from five areas of the field. Determine the average number of PLHs per sweep. Next, take 20 alfalfa stems at random and record the average plant height.

Scouting in dry beans: Walk in an “X” pattern. In 10 areas of the field, pick 10 trifoliate leaves that are newly and fully expanded from the centre of the plant canopy. It is important to note that PLH adults readily fly away when disturbed, which makes them difficult to count on excised leaves.

Thresholds For Potato Leafhopper on Alfalfa

Stem Height2

Number of PLHs per Sweep1

9 cm (3.5 in.)

0.2 adults

15 cm (6 in.)

0.5 adults

25 cm (10 in.)

1.0 adults or nymph

36 cm (14 in.)

2.0 adults or nymph

1 1 sweep = 180° arc.

2 The taller the alfalfa, the more leafhoppers can be tolerated before control is necessary.

Thresholds For Potato Leafhopper on Dry Edible Beans

Bean Growth Stage

# of Adults or Nymphs

per Trifoliate

unifoliate

0.2

2nd trifoliate

0.5

4th trifoliate

1.0

first bloom

2.0

Use a foliar insecticide if thresholds have been reached. A naturally occurring fungal pathogen helps reduce the populations of the PLH under warm, moist conditions but predators and parasites appear to play a minor role in controlling this pest.

It has been a few years since soybean aphids have been noticed in fields this early in the season. This is in part, because many fields were treated with insecticide seed treatments and were assumed to be protecting the crop early in the season. However, very recently published research across several US states has shown that the insecticide seed treatment only lasts in the plant for two weeks or so after planting and soon becomes equivalent to fungicide only treated plants in terms of providing no protection from aphids. This research also confirms that the IPM approach of a well-timed foliar insecticide at threshold in the R1 to R5 stages has greatest yield response.

So bottom line is to not panic when you first find soybean aphids this time of year. It is normal to find them colonizing soybean fields in the early V stages, especially in early planted fields or fields close to buckthorn. Soybean aphids initially start to colonize in pockets of early planted fields. Several plants in these pockets can have hundreds, even thousands of aphids on them at first. Walk a few meters away from these pockets and you won’t find any aphids. Once the aphids start to get crowded on the plants in these pockets, they produce aphids with wings so they can spread out some more, colonizing new plants in the field or leave that field to enter a new one. Aphid counts per plant then change from several hundred per plant in small pockets in the field, to only a few per plant on more plants across the field. This continues to occur, particularly when the plants are still in their V stages. During this time, natural enemies start to notice their presence and will start to feed on these new colonies. Spraying too early when the colonies have just started will delay natural enemy populations from building up and responding to these aphids. Insecticide trials have not been able to show any yield response to sprays done on these V stage infestations. In fact, a spray application during the V stages can actually lead to problems as it easily wipes out the natural enemies that are trying to do the work for you. This results in aphids rebounding quickly and potentially requiring a second spray again once the crop does reach the R stages.

A reminder that the soybean aphid threshold is set for during the R1 to R5 stage of soybeans when research found the an insecticide application is required once 80% of the plants in the field have at least 250 aphids per plant and it is apparent that the population is on the increase. This threshold gives an approximate 7–10-day lead time before the aphids would reach the economic injury level, where cost of control is equal to yield loss. Experience has shown that natural enemies can keep the aphid population fluctuating around the 250 aphid threshold. This fluctuation means they are working hard for you, trying to take down the aphid population. Only when you see that the aphid populations continue to rise instead of fluctuate, do you know that the natural enemies are not plentiful enough to keep up.

More aphids per plant are needed once soybeans are in the R6 stage. Beyond the R6 stage, economic return from any insecticide application is not likely. In good growing conditions when plants are not stressed and are lush, waiting until the aphids are closer to the economic injury level of 600 aphids per plant is possible. In years when plants are stressed and struggling to close the canopy, staying closer to the economic threshold of 250 aphids per plant is advised.

The Aphid Advisor (www.aphidapp.com) is a helpful tool to use when scouting for soybean aphid here in Ontario. Developed by U of Guelph, based on field research conducted in Ontario, it determines if there are enough natural enemies to keep aphid populations in check or if an insecticide application may be needed. Just enter the number of aphids and natural enemies present during R1 to R5 and the app will calculate the potential buildup based on weather and natural enemy presence. Helps to take the guess work out of your spray decision.

True armyworm have been found in a few fields this weekend. Cereals, corn (especially, though not exclusive those fields planted into rye) and mixed forages are at risk and should be scouted every three or four days over the next three weeks. True armyworm identification was covered in a previous blog this spring (here).

Scouting Guidelines:The best time to scout for true armyworm is shortly after dusk when larvae are actively feeding. In corn, examine 20 plants in five areas in the field (100 plants total). In cereals and mixed forages, examine 10 areas of the field, assessing the number of larvae per 30 cm x 30 cm (1 ft2). Pay particular attention to the border area directly adjacent to other grassy host crops. During the day, if it is cloudy and overcast, you might be lucky enough to see larvae in the whorl, leaf axil, or on the head of the plant but on sunny days, they will be down on the ground among the crop debris or under soil clods. Brown frass may also be present on the plants and on the soil surface.

Always take the time to look for any white eggs that may be attached to the backs of the armyworm larvae. This is a sign that the larvae have been parasitized by one of its parasites which have done the job for you. Avoid treating with insecticides when large numbers of parasitized larvae are present.

Fly larvae emerging from an armyworm larva. T. Baute, OMAFRA

Threshold for Corn:Foliar insecticide may be warranted in seedling corn if there are two or more un-parasitized larvae per seedling or 10% or more of the plants have feeding and larvae are smaller than 2.5 cm (1 in.). For corn past the 6-leaf stage; if 50% of the plants have leaf feeding damage and are infested with larvae smaller than 2.5 cm (1 in.), insecticide treatment may be warranted. As long as the growing point of the plant is not damaged, the corn plant is usually able to recover from moderate feeding.

Threshold for Mixed Forages: Control is warranted when five or more larvae (smaller than 2.5 cm) per square foot are found. In seedling crops, two to three larvae (smaller than 2.5 cm) per square foot may warrant control. Avoid treating with insecticides when large numbers of parasitized larvae are present.

Threshold for Cereals: Chemical control is warranted if there are 4 to 5 un-parasitized larvae per 30 cm x 30 cm and the larvae are smaller than 2.5 cm. If a significant amount of wheat head clipping is occurring, spray may be warranted if larvae are still actively feeding, are smaller than 2.5 cm and as long as pre-harvest intervals have not been reached.

If the larvae are over 2.5 cm (1 in.) long, the insecticides will not provide adequate control.

Treatment may be confined to infested areas. If armyworm are migrating from adjacent cereal, mixed forages or corn fields, spraying an insecticide along the field border may be sufficient.

Pay close attention to pre-harvest intervals

]]>http://fieldcropnews.com/2017/06/true-armyworm-scouting-threshold-and-management-guidelines/feed/0Good Year for Seedcorn Maggot and Other Early Season Pestshttp://fieldcropnews.com/2017/06/good-year-for-seedcorn-maggot-and-other-early-season-pests/
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With delayed planting, slower crop emergence and frequent rain events, early season pests get a longer period of time to feed on the seed and seedlings. There are a number of pests causing problems right now.

Gaps in stand and stunted plants are easy to find this spring. T. Baute OMAFRA

Seedcorn maggots are causing injury in both corn and soybean fields. Although higher risk fields include those that have manure or green vegetation incorporated into the soil closer to planting, these are not the only fields showing up with seedcorn maggot injury this year. Unfortunately, no rescue treatments are available for this pest so replanting is the only option to take if plant populations have been significantly impacted. The very warm temperatures (above 30oC) expected next week should help to reduce the maggot and fly activity.

Grubs and wireworms are also very active at the soil surface. Even fields with the high rate of insecticide seed treatment used may experience some injury, as each larva needs to take a bite of the seed or seedling to get a dose of the insecticide before dying. If 4 or 5 larvae bite on one seedling, the plant may not recover. Now is a good time to conduct an Inspection of Soil for those needing access to Class 12 Insecticides. These two pests will be actively feeding for a few weeks still.

Slugs thrive in a wet spring. I wish we had a good management tool for slugs besides tillage. At the very least, moving trash/crop residue away from the seed row can help, as well as ensuring that the seed slots are closed so they don’t have direct access to the seed. But moist soil surfaces help slugs crawl across bare ground. Fortunately, warmer temps next week may help speed up crop development and help the plants get past their vulnerable seedling stages.

If significant crop damage has been experienced in a field that was not planted with a Class 12 insecticide, an Inspection of Crop Pest Assessment can be done to prove need for use of Class 12 insecticide for that farm property for the next 12 months. A professional pest advisor will be required to conduct this assessment to determine if the stand loss thresholds have been met and the assessment only applies for damage incurred by grubs, wireworms, seedcorn maggots or corn rootworms for corn; or grubs, wireworms, seedcorn maggots or bean leaf beetles for soybeans. More information on an Inspection of Crop – Pest Assessment can be found here.

Some field scouts are finding alfalfa weevil above threshold in Niagara and Haldimand counties, though there are likely more fields in other counties at levels of concern. Alfalfa weevil activity usually coincides with first cut but in some years when the crop is slower to develop, the weevil damage gets ahead, causing significant damage before first cut can happen.

Alfalfa weevil larvae are pale to bright green, with a black head and white stripe down the centre of the back. They initially feed within the leaf buds and then move to the tips of the plant. Pinholes are the first signs of damage but can quickly progress to skeletonized leaves. Heavily damaged fields will look greyish white from a distance. Heavy feeding not only impacts yield but also reduces feed quality.

Fields should be scouted twice a week. Fields at greater risk and therefore should be scouted first include those seeded last year, pure alfalfa stands, and areas of the field with south facing slopes.

While walking an M shaped pattern across the field, collect 30 stems by cutting or breaking them off at ground level. Measure the height of the plants. Then using a white pail, shake each plant against the side to knock off the larvae. Count only the 3rd and 4th instar larvae. Smaller 1st and 2nd instar larvae are pale yellow and lack the white stripe along their bodies. Don’t count larvae that are slow moving and are tan or yellow in colour, they are infected by a fungus or parasitoids and will die shortly.

Action Thresholds

No action required:

< 1 active larvae per stem (but continue to monitor)

Action required:

> 1 active larva per stem AND alfalfa < 30 cm (12 in) tall

2 or more active larvae per stem AND alfalfa < 40 cm (16 in) tall

> 3 active larvae at any height.

Cultural Control: If the timing is right and the crop is ready, cutting the crop is the preferred and effective method of control, avoiding the costs of spraying and risk to pollinators and natural enemies. Cutting removes large numbers of larvae while larvae left in the field usually dry out and starve. That said, in heavy infestations, larvae can stick around and cause damage to the early growth of the second crop so scouting is recommended again after first cut.

Cutting before the bud stage, however, can result in extensive damage to second cut regrowth and lower yield. If the crop is not ready to cut, insecticides are the recommended control option.

Insecticides: Registered products are listed here. Spray in the evenings to avoid harming foraging bees and contact local beekeepers prior to spraying so that they can move or protect the hives during the spray. Pay close attention to the days to harvest intervals when selecting and using these products.

]]>http://fieldcropnews.com/2017/05/alfalfa-weevil-alert/feed/0Cereal Leaf Beetle and True Armyworm – the Next Threats for Wheat and Other Cropshttp://fieldcropnews.com/2017/05/cereal-leaf-beetle-and-true-armyworm-the-next-threats-for-wheat-and-other-crops/
http://fieldcropnews.com/2017/05/cereal-leaf-beetle-and-true-armyworm-the-next-threats-for-wheat-and-other-crops/#respondTue, 16 May 2017 17:15:50 +0000http://fieldcropnews.com/?p=13673

Cereal leaf beetle (CLB) is starting to show up in some fields in Ontario. Levels are still low but both adults, eggs and/or larvae are being found by scouts at various locations during routine scouting trips. A few locations tend to experience a higher frequency of infestations including fields near Dresden, Bolton, Stayner, Seaforth, and Clinton. But this does not mean that other fields in Ontario are not at risk. Susan Gowan, a crop consultant in Haldimand, for example. is finding CLB more easily in that county over the last few weeks than in previous years. Nothing of concern yet, but it does indicate that other areas not known for being a CLB hot spot should be scouted. A detailed post on CLB from 2016, including scouting and thresholds can be found here.

True armyworm larvae. T. Baute, OMAFRA

True armyworm is also expected to be a higher risk this year, given very early and higher than normal trap catches this spring, both here and in neighbouring states.

Moths prefer to lay their eggs on grassy vegetation, including grassy weed species, cereals, mixed forages and grassy species of cover crops. Larvae hatch from the eggs and feed at night for approximately a month. Full grown true armyworm are 4 cm (1 1⁄2 in.) long and are dull-green to brown in colour. No matter what colour they are, they always have white-bordered stripes running laterally along the body and to be true armyworm larvae, they must have dark diagonal bands at the top of each abdominal chubby proleg.

There are two to three generations but the first generation is the most problematic here in Ontario. Most feeding activity is done in June to early July but can start as early as late May. In corn, larvae strip the leaf margins, but as they grow in size and numbers, can leave only the midribs left on the plants. As long as the growing point of the plant is not damaged, the corn plant will be able to recover from moderate feeding. In cereals and mixed forages, feeding begins on the leaf margins, but larvae may quickly move up the plant to feed on the kernels and awns or clip the wheat, timothy or other small grains heads completely off of the stem. Clipped heads can be found on the soil surface and can impact yield if taking place in many areas of the field.

The best time to scout for true armyworm is shortly after dusk when larvae are actively feeding. In corn, examine 20 plants in five areas in the field (100 plants total). In cereals and mixed forages, examine 10 areas of the field, assessing the number of larvae per 30 cm2 (1 ft2). Pay particular attention to the border area directly adjacent to other grassy host crops. During the day, if it is cloudy and overcast, you might be lucky enough to see larvae in the whorl, leaf axil, or on the head of the plant but on sunny days, they will be down on the ground among the crop debris or under soil clods. Brown frass may also be present on the plants and on the soil surface.

The storm fronts that pushed up from the southern states over the last month not only carried rain with them but also carried in black cutworm moths. Trap catches have been higher than normal this year in neighbouring states, indicating a higher risk this spring for Ontario. Once they arrive, the adult moths look for weedy green patches in fields to lay their eggs on. Fields at risk include those with pre-plant annual weeds (eg. chickweed, mustards, volunteer wheat, lamb’s-quarters, velvetleaf etc), cover crops or crop residue. Delayed burn downs increase the risk of injury, as the larvae feed on the existing plants and weeds while waiting to move over to the corn crop once it emerges. Fields near Lake Erie tend to have more frequent infestations from moths dropping down as soon as they cross the lake, but infestations are not exclusive to fields in that area.

Leaf feeding damage by young black cutworm larvae. T Baute, OMAFRA

Young larvae feed on the corn leaves, leaving small pinholes but eventually take bigger chunks from the leaf margins, given the plant the appearance of hail damage. Larger larvae also hollow out the stalk of the small plants or cut them off at or below the soil line, causing the plant to wilt or be left laying on the ground. The longer the delay before crop emergence, the larger the larvae will be moving over to the crop. In this scenario, you are less likely to see the early feeding leaf feeding damage and instead find plants being cut off at or below the soil line. Once the crop is in the V5 stage, the growing point of the plant is above ground and can tolerate most of the injury and the larger larvae are slowing down in their feeding, only cutting a few more plants before pupating.

Corn plant cut off at soil level by black cutworm. A Schaafsma, UGRC

Seed treatments containing clothianidin (eg. Poncho), cyantraniliprole (i.e. Fortenza) and chlorantraniliprole (i.e. Lumivia) provide early protection. Bt hybrids containing Cry1F or Vip3A also provide protection against black cutworm. So focus first on scouting those fields not planted with one these control options. Foliar insecticide treatments can provide effective control, if applied at threshold and before larvae are larger than 2.5 cm. Inspect 20 plants in five areas of the field once or twice per week from VE until the crop is into the V5 stage. Look for pinholes or notches on the leaves, or wilting or cut plants. Dig the soil around the injured plant to find the larvae which hide in the soil during the day.

Foliar threshold: Control is warranted if 10% of plants in the V1 toV4 stage have damaged leaves/pinholes or 3% or more plants are cut and larvae are smaller than 2.5 cm. Insecticides are not effective on larvae larger than 2.5 cm.

Calling all WBC Trap Participants! The WBC Trap Network website is now up and running and ready for you to add your trap sites and join our trapping network.

Anyone wishing to join must login and create a new user account at www.cornpest.ca. Click on the “Login” menu from the top left of the page (on a computer) or from the top right of the page (using a mobile device). This will take you to the site’s login page. Scroll to the bottom of the login page and there you will find a link to “Create a new Account” page. Note that all usernames, by default, will begin with “CP-” followed by your email address (eg. CP-johnsmith@hotmail.com). More detailed instructions on how to login and create an account has been provided here.

For each corn field, you will need one trap. For each dry bean field, you will need two traps. We prefer bucket traps (aka uni-traps) instead of the milk jug traps which are more labour intensive and must have antifreeze in them at all times work. Detailed trapping instructions and trap supply lists and sources are also provided on the website at: http://www.cornpest.ca/wbc-trap-network/wbc-trapping-instructions/

Enter your trap data no later than Wednesday of each week, entering the previous weeks counts and in return, we will have interactive maps published for all data coming in from Ontario, Quebec and new this year Michigan! Traps need to go up sometime in June and stay up until the end of August.

And finally, we have revised the WBC infosheets for both corn and dry beans. Here are the links to those resources:

Soil temperatures are at 10 degrees C which means that wireworms and grubs are active near the soil surface. So it is also a great time to set up wireworm baits or dig for grubs.

Wireworm Larva. A. Schaafsma, UGRC

For the 2017 planting season, growers wanting to purchase and plant neonic treated corn and soybean seed require a pest assessment report (PAR) through an Inspection of Soil. PARs are valid for 12 months from the day that the assessment was completed so if you have a report that hasn’t expired yet for the same 100 acres or less on farm property identified in the report, it can still be used this season to purchase the seed to be planted on that 100 acres.

If a new PAR is needed, the inspection of soil must be conducted by an IPM certified person who has taken the course at: https://www.ipmcertified.ca/. The person who purchases the seed must also be an IPM certified person. Starting August 31st, 2017, those farm properties within the counties identified in Schedule 1 will require a Professional Pest Advisor to conduct the inspection of soil for the 2018 growing season.

A reminder from a previous post on how to conduct an Inspection of Soil is below, including various resources that you may find helpful.

Soil Inspection Pest Assessment – For every 100 acre or less plot on a farm property, baits or digging need to be done in 5 areas of the field. Look for higher risk areas of the fields to focus your scouting efforts, though each of the 5 scouting areas need to be 10 metres apart from each other. High risk areas of the field include sandy or silty areas of the field, especially knolls, areas where grassy weeds are prevalent, or in areas where gaps in the stand have been noticed in the past.

Wireworm bait station using 1 cup of flour

To set up wireworm baits:

Dig a hole approx 15 cm by 15 cm by 15 cm deep

Place a cup of bait in the bottom of the hole. Baits can be made of:

1 cup of all-purpose flour – moisten with some water once placed in the hole or

1 cup of equal parts of untreated corn, wheat and beans that has been soaked overnight.

Break up any clumps of soil that was dug up and mound the soil over the bait.

To deter predators and keep the bait moist and warm, place a black plastic bag over the bait station and cover the corners of the plastic with soil so that it doesn’t blow away.

Place a flag at the station so you can find it again.

Return 7 to 10 days later to dig up the bait. Break up the bait to search for the presence of wireworms.

Do this for at least 5 locations in the 100 acre or less plot, each bait station being at least 10 metres apart from each other. Experience has taught us that predators like to pull up the baits so place more than is required to ensure that there are five still left to assess.

To dig for wireworms or grubs:

Grubs can be found close to the soil surface in both spring and fall

Dig a hole approximately 30 cm by 30 cm wide to about 7 to 10 cm deep.

Sift through the soil that was removed from the hole, breaking up any larger clumps.

Search and record any wireworms or grubs found in the hole or the soil that was removed.

Do this digging method for at least 5 locations in the plot, each location being at least 10 metres apart from each other.

Remember, don’t confuse millipedes for wireworms. Click here to see the differences.

The threshold to purchase and use (plant) neonicotinoid treated corn or soybean seed is an average of 1 wireworm or 2 grubs averaged over 5 scouting locations per 100 acre plot. If this threshold is met, fill out the Inspection of Soil – Pest Assessment Report and provide a copy to your seed vendor(s).

Of note is the removal of western bean cutworm from products within the table containing only the Cry1F trait as this trait no longer provides adequate protection against WBC. Only hybrids containing Vip3A provide protection against WBC now. If you are planting a corn hybrid this year that does not contain Vip3A, expect to scout for WBC egg masses this summer and spray if thresholds are reached.

More information on WBC monitoring, scouting and management to come soon. The CCPC website is currently down for maintenance/refresh. We hope to have both the CCPC website and the WBC Trap Network up in early May. In the meantime, any relevant information on WBC and the trap network will be provided here at FieldCropNews. So stay tuned!